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Unformatted text preview: I. Ch.3 The Origin of Species A. According to creationism, the biological characteristics of all life forms were divinely created during six days of Creation (described in Genesis, the first book of the Bible) and therefore are immutable. B. Carolus Linnaeus developed the first biological classification (taxonomy) of plants and animals based on similarities and differences in their physical characteristics.In the 18th and 19th centuries, the discovery of fossils from species that no longer existed, as well as the absence of contemporary species in the fossil record, raised doubts about creationism. C. According to catastrophism, a modified version of creationism, ancient species were destroyed by fires, floods, and other catastrophes and then replaced by new, divinely created species. D. Theory and Fact 1. Evolutionists rejected creationism and catastrophism, believing instead that species arose from others through a long and gradual process of transformation, or descent with modification. 2. Charles Darwin, the best-known evolutionist, was influenced by Charles Lyell's concept of uniformitarianism. 1. Uniformitarianism states that explanations for past events should be sought in the long-term action of ordinary forces that still work today. 2. Uniformitarianism further asserts that current geological features such as mountain ranges are the result of long-term natural forces. 3. Darwin applied the ideas of uniformitarianism and long-term transformation through natural forces to living things, arguing that all life forms are ultimately related and that the number of species is not immutable but has increased over time. 3. A theory is a set of ideas formulated (by reasoning from known facts) to explain something. The main value of a theory is to promote new understanding. The fact of evolution (that evolution has occurred) was known earlier. The theory of evolution, through natural selection (how evolution occurred), was Darwin's major contribution. 4. Natural Selection 1. Darwin and Alfred Russel Wallace offered natural selection as a single principle that could explain the origin of species, biological diversity, and similarities among related life forms. 2. Natural selection is the process by which forms most fit to survive and reproduce in a given environment do so in greater numbers than others in the same population. 3. For natural selection to work on a given population, there must be variety within that population as well as competition for strategic resources (those necessary for life) among members of the population. 4. Organisms whose attributes render them fitter to survive and reproduce (thereby transmitting their genetic material to future generations) in a given environment will do so in greater numbers than organisms that are less fit....
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